System and method for friend or foe identification

ABSTRACT

A system for use in identifying one of an unmanned ground vehicle and an unmanned aerial vehicle includes a signal emitter associated with the unmanned vehicle. The signal emitter includes at least one quantum cascade laser. The signal emitter emits a signal having a wavelength between approximately 2 μm and approximately 30 μm, and the signal is detectable to identify the unmanned vehicle as friendly at a distance from the signal emitter greater than approximately 1 meter.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.13/053,993, filed Mar. 22, 2011, entitled “SYSTEM AND METHOD FOR FRIENDOR FOE IDENTIFICATION,” which is a non-provisional application based onU.S. Provisional Application No. 61/316,144, filed Mar. 22, 2010, theentire disclosures of each of the above applications are incorporatedherein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A “SEQUENCE LISTING”

Not applicable.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to signal emitting devices and, inparticular, devices useful in friend or foe identification.

Description of Related Art

Unmanned vehicles are heavily used in various environments forreconnaissance, aerial photography, combat activities, rescue efforts,and other purposes. For example, an unmanned vehicle (“UV”) may be areconnaissance aircraft, drone, unmanned aerial vehicle, or other likedevice that can be controlled remotely to fly over and/or otherwise inthe vicinity of unfriendly forces, contaminated terrain, or otherpotentially dangerous areas. As another example, a UV may be a groundvehicle, robot, or other like device that can be controlled remotely totravel and maneuver, via land and/or sea, proximate such potentiallydangerous areas. Such exemplary devices include, for example, the BigDogand other rough-terrain robots manufactured by Boston Dynamics ofWaltham, Mass., the PackBot manufactured by iRobot of Bedford, Mass.,and other similar devices.

Until recently, friendly reconnaissance groups, rescue groups, lawenforcement groups, combat personnel or other friendly forces were theonly users of UVs. However, UVs are now becoming more widely used byunfriendly or foe opposition groups. Such groups are finding itincreasingly easy to equip these UVs with harmful equipment or devices,thereby putting friendly forces at risk. In some environments it can bedifficult for friendly forces to distinguish between friendly UVs andfoe UVs, and this difficulty can be heightened under the stress ofcombat situations.

It is understood that known markers, locating lasers, beacons, or otherlike signal emitters can be connected to and/or otherwise associatedwith such UVs to assist in locating and/or identifying UVs at moderatedistances. However, these known signal emitters are plagued by a host ofdebilitating drawbacks that make them inefficient or potentiallydangerous for use in combat arenas. For instance, while many signalemitters are clearly visible by conventional night vision goggles orother like viewing devices, such viewing devices are widely availableand used by both friendly forces and unfriendly groups. Thus, friendlyUVs equipped with known signal emitters can be detected by theunfriendly groups, making stealth operation of such UVs difficult, ifnot impossible.

In addition, most known signal emitters are not easily programmable ormodifiable in the field, and are not configured to emit a diverse rangeof, for example, pulse signatures, beams, or signals. As a result, it isrelatively easy for unfriendly groups to “disguise” their UVs byprogramming the signal emitters associated with such UVs to emitsubstantially the same signature or signal as that emitted by, forexample, a friendly signal emitter. Such ease of deception can be verydangerous in certain environments.

Moreover, some known signal emitters, such as thermal markers or otherdevices emitting radiation, pulse signatures, or other signals in thethermal band, may have a limited detection range. For example, whilefriendly forces and UVs may be equipped with known thermal markers forfriend or foe identification, the signals emitted by these devices maynot be easily detected beyond a range of several hundred meters. Thisrange may be relevant in a tightly confined arena of engagement, butsuch a limited range can put friendly forces at risk when UVs are used.For example, UVs such as the BigDog or unmanned aerial vehiclesdiscussed above can move at high rates of speed and may approach oroperate (in the case of unmanned aerial vehicles) at distances greaterthan 1 km from the combat arena. Not being able to detect a UV, ordetermine whether or not the detected UV is friendly, unless and untilthe UV is within several hundred meters of, for example, an engagementarena or other area occupied by friendly forces, can put these forces atserious risk.

Moreover, devices used in military, law enforcement, surveillance, andother industries may also employ signal emitters in various environmentsto mark an object or location, and/or to otherwise convey informationabout the object or location. Such devices may include, for example,unattended ground sensors/devices, self-righting camera balls such asthe Eye Ball R1 Surveillance Ball manufactured by Remington ArmsCompany, Inc. of Madison, N.C., and other like devices. Moreover, suchinformation may include, for example, whether or not to engage theobject, or the location of a target, hidden resources, friendly forces,or checkpoints along a path. However, known signal emitters may not besuitable for use with such devices due to the deficiencies discussedabove. For example, signals emitted by thermal markers may not be easilyseen from great distances, thus making locating such devices difficult.

The various embodiments set forth in the present disclosure are directedtoward overcoming the problems discussed above.

BRIEF SUMMARY OF THE INVENTION

In an exemplary embodiment of the present disclosure, a system for usein identifying one of an unmanned ground vehicle and an unmanned aerialvehicle includes a signal emitter associated with the unmanned vehicle.The signal emitter includes at least one quantum cascade laser. Thesignal emitter emits a signal having a wavelength between approximately2 μm and approximately 30 μm, and the signal is detectable to identifythe unmanned vehicle as friendly at a distance from the signal emittergreater than approximately 1 meter.

In a further exemplary embodiment of the present disclosure, a method ofidentifying one of an unmanned ground vehicle, an unmanned aerialvehicle, and an unmanned aqueous vehicle includes detecting a signalemitted by a signal emitter associated with the unmanned vehicle from adistance greater than approximately 1 meter. The signal emitter includesa quantum cascade laser, and the signal has a wavelength betweenapproximately 2 μm and approximately 30 μm. The method also includesidentifying the unmanned vehicle as friendly based on one or moreobservable characteristics of the detected signal. Such a method alsoincludes modulating the signal to indicate the unmanned vehicle as beingone of a plurality of friendly vehicles. Additionally, in such a methodthe observable characteristic of the signal is encrypted by temporallymodulating the signal.

In another exemplary embodiment of the present disclosure, a system foruse in identifying a location of interest and emitting a signalcontaining information regarding the location includes a handheld signalemitter including a quantum cascade laser. The signal emitter isconfigured to emit the signal in response to a command. The signal has awavelength between approximately 2 μm and approximately 30 μm, and isdetectable to convey the information at a distance from the signalemitter greater than approximately 1 meter.

In another exemplary embodiment of the present disclosure, a system foruse in identifying a location of interest and emitting a signalcontaining information regarding the location includes a signal emitterassociated with one of a portable self-righting device and a portableunattended ground device, the device configured to be transported to anddesirably positioned at the location, the signal emitter including aquantum cascade laser. The signal emitter is configured to emit thesignal in response to a command. The signal has a wavelength betweenapproximately 2 μm and approximately 30 μm, and is detectable to conveythe information at a distance from the signal emitter greater thanapproximately 1 meter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic view of a signal emitter according to an exemplaryembodiment of the present disclosure.

FIG. 2 is a schematic view of a signal emitter according to anotherexemplary embodiment of the present disclosure.

FIG. 3 illustrates a system for use in identifying an unmanned device,including an emitter disposed on an unmanned aerial vehicle according toan exemplary embodiment of the present disclosure.

FIG. 4 is another view of the system shown in FIG. 1.

FIG. 5 illustrates a system for use in identifying an unmanned device,including an emitter disposed on an unmanned ground vehicle according toanother exemplary embodiment of the present disclosure.

FIG. 6 illustrates a system for use in identifying an unmanned device,including an emitter disposed on a self-righting camera ball accordingto yet another exemplary embodiment of the present disclosure.

FIG. 7 illustrates a system for use in identifying an unmanned device,including an emitter disposed on an unattended ground sensor accordingto a further exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a signal emitter 14 according to an exemplaryembodiment of the present disclosure. The signal emitter 14 may emit asignal in the optical portion of spectrum or in the thermal band. Inaddition, the beam can be a continuous wave, a temporally modulatedbeam, or a temporally encoded signal, wherein the temporally encodedsignal can be encrypted or unencrypted. Thus the signal emitter 14 maybe, for example, any type of signal emitter capable of emitting a signalin the form of one or more thermal or optical beams, pulses, or otheridentifiable signal types. Such an optical beam may have a wavelengthbetween approximately 0.3 μm and approximately 2 μm, and such a thermalbeam may have a wavelength between approximately 2 μm and approximately30 μm.

In an exemplary embodiment, the signal emitter 14 may emit a signalbetween approximately 2 μm and approximately 30 μm, and the signal maybe detected within a range of approximately 4 km or greater. Inadditional exemplary embodiments, the signal may be detected within arange of approximately 1 meter or greater. As shown in FIG. 1, such anexemplary signal emitter 14 may comprise a quantum cascade laser (“QCL”)30 or other signal source known in the art. The signal emitter 14 mayalso include a housing 20, a driver 40, a cooler 50, a lens 60, and apower supply 70.

The housing 20 can be configured for handheld use, firearm mounting, ormounting to any of the unmanned devices 12 discussed herein. The housing20 is selected to encompass at least one of the QCL 30, the driver 40,the cooler 50, the lens 60, and the power supply 70. In oneconfiguration, the housing 20 encompasses (retains) all the componentsrequired for operation of the QCL 30. That is, the housing 20 providesthe signal emitter 14 as a self-contained, handheld, and/or otherwiseportable device.

The housing 20 can include an aperture 21 for emission of a beam orother signal from the QCL 30. In addition, the housing 20 can includeone or more apertures, switches, connectors, or ports 23 forcontrolling, activating, deactivating, and/or powering the signalemitter 14. The ports 23 may comprise, for example, an on/off switch,switches or controls for operating mode selections, and/or powerconnectors configured to assist in connecting the signal emitter 14 to apower supply 80 of the unmanned device 10 to which the signal emitter 14is connected. Each of the ports 23 may be connected to the driver 40through any known electrical connection such that power, controlcommands, or other signals may be communicated from the ports 23 to thedriver 40. Such ports 23 may facilitate remote activation and/ordeactivation of the signal emitter 14. As will be described in greaterdetail below, the signal emitter 14 may further include any combinationof transponders, antennas, power circuits, receivers, and/or other knowncomponents to facilitate such remote control and/or operation. Suchcomponents may also assist in, for example, conserving stored energy ofthe power supply 70. For example, the signal emitter 14 may beconfigured to operate in a relatively low current mode of operationuntil receiving an activation signal. Upon receipt of such a signal, thesignal emitter 14 may, for example, change modes and begin emitting adesired signal.

The housing 20 can be formed of any of a variety of rigid material suchas composites, laminates, plastics or metals. In one configuration, thehousing 20 may be formed of an extruded aluminum, thereby providingsufficient strength without requiring significant weight. However, it isunderstood the housing 20 can be machined such as by EDM (electricaldischarge machining) or molding if composites, laminates, plastics oreven metals are employed for the housing 20. The housing 20 may besubstantially watertight so as to protect the components disposedtherein from water or other harmful contaminants found in ruggedenvironments such as combat arenas.

In one configuration of the signal emitter 14, the housing 20 may beconfigured to mount to any of a variety of handheld, side, and smallfirearms. Such firearms include, but are not limited to, pistols,rifles, shotguns, automatic arms, semi-automatic arms, and bows. Forexample, the housing 20 may be configured to mount to any known sidearm,as well as any known dismounted crew-served weapon, such as machine gunsand the like. The housing 20 can interface with any of a variety ofclamping or mounting mechanisms such as a Weaver-style Picatinny rail ordove tail engagement for mounting to these firearms.

Alternatively, as discussed above, the housing 20 may be configured tomount to any of a variety of unmanned devices 12 used in surveillance,law enforcement, reconnaissance, target marking, friendly force marking,or combat applications. As illustrated more clearly in FIGS. 3-7, suchunmanned devices 12 include, but are not limited to, any of the UVsdiscussed herein, unattended ground sensors, self-righting camera balls,and other like devices. In additional exemplary embodiments, any and/orall components of the signal emitter 14 may be integrally incorporatedinto such devices 12. In such embodiments, the housing 20, or portionsthereof, may be omitted if desired. For example, in an embodiment inwhich the signal emitter 14 is formed integrally with a robot, UV,unmanned aerial vehicle, unattended ground sensor, or other like device,the components of the signal emitter 14 may be hermetically sealedwithin such devices and the housing 20 may be omitted to reduce size,weight, space, power consumption, and/or drag associated with the signalemitter 14. In such embodiments, one or more windows, lenses, domes, orother components may be employed proximate an outer surface of thedevice 12 to facilitate emission of radiation from the integral signalemitter components.

Such unmanned devices 12 may further include marking devices capable ofmarking, for example, a trail or path, an intended target, the locationof friendly forces, distressed friendly forces in need of assistance,and/or a perimeter, or other relevant areas or items. Such markingdevices may include, for example, unmanned robots capable of stealthilyapproaching unsuspecting targets and marking the location of suchtargets. Other such marking devices may be relatively small deviceseasily carried and set on the ground or in other typical locations bysoldiers traversing a complicated trail or path.

With continued reference to FIG. 1, the QCL 30 is retained within and/orotherwise connected to or associated with the housing 20. The QCL 30 maybe configured, via the lens 60, to produce a beam extending along a beampath. It is understood that any of a variety of lenses, 60, windows,domes, diffraction gratings, filters, prisms, mirrors, and/or other likeoptical components, or combinations thereof, may be disposed opticallydownstream of the QCL 30 along the beam path. Due to their positionalong and/or within the beam path and optically downstream of the QCL30, radiation emitted by the QCL 30 may pass through, be shaped by,and/or otherwise optically interact with such optical components beforeexiting the housing 20. In an exemplary embodiment, one or more lenses60 of the type described herein may be positioned in the beam path andoptically upstream of a window, dome, or other like optical component.The beam path may extend from the QCL 30, through a portion of thehousing 20, to pass to the exterior of the housing 20.

It is understood that the QCL 30 and/or the lens 60 may be disposed at aportion of the housing 20 configured to assist with cooling the QCL 30during operation. For example, as shown in FIG. 2, the housing 20 maydefine one or more extensions 25 or other like structures configured toassist in cooling the QCL 30 through, for example, contact with movingair, and such an embodiment may be useful when connecting the signalemitter 14 to, for example, a relatively fast moving unmanned device 12such as an unmanned aerial device or an unmanned ground device. Such anextension 25 may be thermally connected to the QCL 30 and may furtherinclude, for example, one or more passive cooling devices such as heatsinks, fins, phase change material, or other like devices also thermallyconnected to the QCL 30. In still another exemplary embodiment, the lens60 may be omitted, and the radiation or other signal produced by the QCL30 may be widely divergent based on the nature and configuration of theQCL 30 itself. It is understood that regardless of the housingconfiguration, and notwithstanding the presence or omission of the lens60, window, dome, or other like structure, the QCL 30 may be maintainedin a hermetically sealed environment during use.

The QCL 30 may be selected to operate in ambient temperature conditionswhile producing a beam or other such signal having a wavelength betweenapproximately 1 μm and approximately 30 μm, with a preferred wavelengthof approximately 2 μm to approximately 5 μm or approximately 7 μm toapproximately 30 μm. Although a single QCL 30 is shown in housing 20, itis contemplated that a plurality of QCLs can be disposed within thehousing 20, some or all of the QCLs emitting radiation at differentrespective wavelengths. In additional exemplary embodiments, a singleQCL 30 can be employed with an appropriate driver 40 and/or filter toprovide a plurality of corresponding wavelengths.

The QCL 30 may exhibit the electrical behavior of a semiconductormaterial which can be described with the band model. This model statesthat various energy ranges, or energy bands, are available to theelectrons of the semiconductor material, and that the electrons of thesemiconductor material can essentially take on any energy value withinthe energy bands. Various bands can be separated from one another by aband gap, i.e., an energy band with energy values the electrons cannotpossess. If an electron changes from a higher energy band to a lowerenergy band, energy corresponding to the difference of the energy valuesof the electron before and after the change, which is also called“transition”, is released. The energy difference can be released in formof photons. The band with the highest bound-state energy level, which isfully filled with electrons at a temperature of 0° Kelvin, i.e., theso-called valence band, and the conduction band that is energeticallyabove the valence band, which is unfilled at 0° Kelvin, as well as theband gap between them are of special significance for a semiconductormaterial.

In the cascades of QCLs, the semiconductor materials for the barrierlayers and the quantum wells are selected such that the lower conductionband edge of the barrier material lies higher in energy than the lowerconduction band edge of the quantum well material. The lower conductionband edge represents the lowest energy value that an electron can assumewithin the conduction band. The energy difference between the energy ofthe lower conduction band edge of the barrier material and the lowerconduction band edge of the quantum well material is also called theconduction band discontinuity. As a result of this selection, theelectrons of the quantum wells cannot readily penetrate the barrierlayers and are therefore enclosed in the quantum wells. The electronscan only “tunnel” through a barrier layer into an adjacent quantum wellin a quantum-mechanical process, with the probability of the occurrenceof a tunneling process depending on the height of the conduction banddiscontinuity and the thickness of the barrier layer between the twoquantum wells.

In the quantum well, the behavior of the electrons enclosed in the wellis determined by quantum mechanics effects due to the small thickness ofthe layer (only a few nanometers). An essential effect is that theelectrons in an energy band of the quantum well can no longer assume anyenergy value within the energy range of the band, but rather areconfined to the energy values of specific energy levels, i.e.,sub-bands. The energetic differences between the individual sub-bandsare particularly high if the quantum well is very thin and theconduction band discontinuity is high. The electron energy does notchange continuously, but rather jumps from one sub-band to the next. Theelectron can change from one energy level to the other energy level onlyif the energy increase or the energy decrease suffered by an electroncorresponds precisely to the difference of the energy values of twosub-bands. Transitions from one energy level to another energy levelwithin one and the same band are called intersubband transitions. In thecascades of the QCL, the emission of laser radiation occurs at theseintersubband transitions. For emission of signals having wavelengthsbetween approximately 2.9 μm and 5.3 μm at room temperature, the QCL 30as set forth in U.S. Publication No. 2005/0213627, published Sep. 29,2005, assigned U.S. patent application Ser. No. 11/061,727, filed Feb.22, 2005, is hereby expressly incorporated by reference.

In one configuration, the QCL 30 or other signal sources of the presentdisclosure may be hermetically sealed within the housing 20, therebyproviding a controlled humidity and atmosphere for operation of the QCL30. Such hermetic sealing can include a subhousing or potting of the QCL30. The sealing can include a sealing of the housing 20, a sealing ofthe QCL 30 as the QCL 30 is retained within the housing 20, or both.

In a further exemplary embodiment, the signal or beam source of thesignal emitter 14 may comprise an infrared laser (such as at 830 nm)and/or a visible laser (400 nm to 750 nm), such as a model HL6321MGlaser manufactured by Hitachi. In such exemplary embodiments, the QCL 30may be omitted. It is further understood that the QCL 30 may be replacedwith one or more carbon dioxide lasers. Such lasers may be useful in anyof the applications discussed herein, and may be particularly useful inconjunction with any of the marking devices discussed herein.

In a further configuration, the QCL 30 can be tuned to provide a signalor beam of a specific wavelength, and/or to provide a signal having apulse or other signature easily recognizable by U.S. or otherfriendly/allied forces. Tuning of the signal or beam emitted by the QCL30 can be accomplished by locating a grating in the signal or beam path.The grating can be adjustable to allow selective transmission of a givenwavelength, or fixed to transmit only a single wavelength. Although thesignature of the signal or beam emitted by the QCL 30 may be preset, thesignature, wavelength, frequency, pulse pattern, and/or otheridentifiable and distinguishable characteristics of the signal or beammay be easily tunable in the field and/or during use. Such ease oftunability may substantially reduce or eliminate, for example, theability of enemy forces to disguise foe signal emitters as friendlysignal emitters 14. In addition to the grating discussed above, it isunderstood that the driver 40 may be configured to assist in tuningand/or otherwise controlling the output of the QCL 30.

The driver 40 can be constructed to provide either pulsed or continuouswave operation of the QCL 30. The rise/fall time of the pulse,compliance voltage and current for the QCL are selected to minimizepower consumption and heat generation. These parameters may also beselected to produce a desirable beam or signal signature for friend orfoe identification. The driver 40 may be located within the housing 20,and may be operably connected to the QCL 30, the cooler 50, and/or thepower supply 70. Alternatively, the power supply 70 may be omitted andthe driver 40 may be operably connected to a power supply 80 of thedevice 12 to which the signal emitter 14 is connected. The driver 40 mayinclude a pulse generator, an amplifier, a pulse switcher, and/or otherknown driver components.

The driver 40 may enable operation of the QCL 30 as a pulsed laser, suchas by passive, active, or controlled switching. Although specific valuesdepend upon the particular QCL 30 and intended operating parameters, itis contemplated the peak power draw of the driver 40 may be betweenapproximately 1 amp and approximately 10 amps, with an average currentdraw between approximately 0.01 amps and approximately 0.1 amps. As therequired voltage may be between approximately 9 volts and approximately12 volts, approximately 9 W and approximately 120 W may be consumed.This may represent a substantial power consumption as well as heatgeneration. Accordingly, in an exemplary embodiment it may be desirableto omit the power supply 70 of the signal emitter 14, and instead,utilize the power supply 80 of the unmanned device 12.

In an exemplary embodiment, the driver 40 may assist in controllingand/or modifying the power level of the QCL 30 to aid in penetratingcomponents or conditions of the atmosphere in which the signal emitter14 is used. Such components or conditions may include, for example,snow, rain, fog, smoke, mist, clouds, wind, dust, gas, sand, and/orother known atmospheric or airborne components. For example, the driver40 may be configured to controllably, manually, and/or automaticallyincrease the current and/or voltage directed to the QCL 30 to strengthenand/or intensify the beam or signal emitted by the QCL 30 in suchconditions. It is also understood that the signal emitter 14 maycomprise at least one midrange QCL and at least one long range QCL toensure satisfactory operation in such conditions.

In an exemplary embodiment, the QCL 30 may be pulsed at frequencies lessthan a millisecond. However, it is understood that, depending upon theintended use and range of the signal emitter 14, the repetition rate,peak power, beam, signal, and/or other distinguishing characteristics ofthe QCL output can be factory set or programmable/modifiable in thefield as needed.

The lens 60 may be disposed in the beam or signal path 32 such that inone configuration, the lens 60 is retained substantially within thehousing 20. However, it is contemplated the lens 60 can form aninterface between the interior and the exterior of the housing 20. Instill another exemplary embodiment, a window, the lens 60, and/or theQCL 30 may be disposed in an extension 25 of the housing 20 configuredto assist in cooling the QCL 30. As discussed above, such an embodimentis illustrated in FIG. 2. The lens 60 can be configured to focus thebeam or signal at a particular point. Alternatively, the lens 60 may beconfigured to spread or diverge the signal or beam as broadly aspossible to maximize coverage. Alternatively, the lens 60 may be omittedfrom the signal emitter 14, and the QCL 30 may be configured as awidely-divergent beam or signal source. In such an embodiment, a window,dome, or other like structure may be employed such that the QCL 30operates in and/or is otherwise maintained in a hermetically sealedenvironment. In one or more of these exemplary embodiments, the lens 60can be a dedicated collimator, thereby collimating the beam or signalalong the path 32. The lens 60 may be formed of a material substantiallytransparent to the wavelength of the beam or signal emitted by the QCL30.

In an alternative configuration, a diffractive optic (not shown) can belocated within the beam path 32 to provide collimation of the beam. Thatis, the diffractive optic may intersect the beam path 32 such that thebeam passes through or reflects off the diffractive optic.

In an exemplary embodiment, the power supply 70 may include at least onebattery. Depending upon the anticipated power requirements, availablespace, and weight restrictions, the batteries can be N-type batteries orAA or AAA batteries. Additionally, a lithium/manganese dioxide batterysuch as military battery BA-5390/U, manufactured by Ultralife BatteriesInc. of Newark, N.Y. can be used with the signal emitter 14. It isunderstood that any type of power supply 70, preferably portable andsufficiently small in size for use with any of the devices discussedherein, can be utilized. The battery-type power supply can be disposableor rechargeable.

The power supply 70 may be located within or external to the housing 20.In one configuration, the housing 20 may include a battery compartmentsized to operably retain the power supply 70. The battery compartmentcan be formed of a weather resistant, resilient material such asplastic, and shaped to include receptacles for receiving one or morebatteries or other power storage devices. Further, the batterycompartment may be selectively closeable or sealable to preventenvironmental migration into the compartment.

The power supply 70 may be operably connected to the driver 40 and canbe controlled by or utilized under driver commands. Thus, the amount ofpower from the power supply 70 can be controlled or varied to alter theoutput of the QCL 30. As discussed above, however, the signal emitter 14and each of its components may also be powered by one or more powersupplies 80 of the device 12 to which the signal emitter 14 isconnected. In such an exemplary embodiment, the power supply 70 may beomitted, and the driver 40 and/or other power distribution devices ofthe signal emitter 14 may distribute power from the power supply 80 tothe signal emitter components.

In a further configuration, a cooler 50 can be disposed in thermalcontact with the QCL 30. The cooler 50 may be disposed within thehousing 20, and may be employed to maintain the QCL 30 at a desirableoperating temperature. As certain configurations of the cooler 50require energy input, it is advantageous that the housing 20, the QCL 30and the driver 40 be configured to minimize thermal demands on thecooler 50. For example, at least a portion of the QCL 30 may be disposedoutside of the housing 20 such that the QCL 30 is at least partiallycooled by wind, atmospheric temperature, water, or other aspects of theexternal environment in which the signal emitter 14 is used. In anexemplary embodiment, the cooler 50 may assist in cooling the QCL 30 toapproximately room temperature or between approximately 65° Fahrenheitand approximately 75° Fahrenheit. In additional exemplary embodiments,the cooler 50 may be configured to cool the QCL 30 to temperatures belowroom temperature, such as to approximately 32° Fahrenheit or lower. Insuch exemplary embodiments, one or more barriers, seals, walls,compartments, absorbent materials, and/or other like components may beemployed proximate the QCL 30 to assist in isolating the QCL 30 from anycondensation or moisture formed on and/or by the cooler 50. Suchcomponents may be included within the housing 20, or in alternativeexemplary embodiments in which the signal emitter 14 is formedintegrally with the device 12 and at least a portion of the housing 20has been omitted, such components may also be disposed within and/orformed integrally with the device 12. The cooler 50 may comprise athermoelectric cooler or any other cooler known in the art.

The cooler 50 can be a passive device or an active device. A passivecooler 50 may comprise a heat sink, a phase change element, a radiator,and/or one or more fins configured to dissipate thermal energy from theQCL 30. As used herein, a “phase change element” may include any elementand/or material configured to absorb heat energy and utilize theabsorbed energy to change the phase of, for example, a solid to aliquid. An active cooler 50 may comprise a Peltier module, a Stirlingdevice, and/or one or more fans.

In a further exemplary embodiment, the signal emitter 14 may include acommunicator 90 such as a receiver, a transmitter, and/or a transceiverfor receiving and/or transmitting information from a remote source 92.As described above, such components may be operably connected to and/orconnectable via one or more of the ports 23. Such information caninclude targeting data, strategic data, signaling data, emission data,operating or control signals, and/or other like data or signals usefulin combat, law enforcement, reconnaissance, stealth location, or markingexercises. The communicator 90 may be operably connected to the powersupply 70, 80 as well as well as the driver 40. Accordingly, the signalemitter 14 may be capable of communicating with the remote source 92 viathe communicator 90. The communicator 90 and the remote source 92 may becapable of radio and data transmission at wireless frequencies, and/orother communication for the transmission of information, data, controlsignals, and the like. In an exemplary embodiment, such control signalsmay include on/off commands as well as control commands for remotelychanging the pulse signature, frequency, wavelength, and/or othercharacteristics of the beam or signal emitted by the QCL 30. It isunderstood that corresponding functions or operations of the QCL 30and/or the driver 40 may be changed or controlled in response to suchcontrol signals.

FIGS. 3-5 illustrate exemplary systems 10 to aid in identification of anunmanned device 12 as either friend or foe. FIGS. 6 and 7 illustrateexemplary systems 10 for use in marking, identification and/or otherwiseconveying information about a location or object. The systems 10 shownin FIGS. 3-7 may include, for example, among other things, a signalemitter 14 coupled to, formed integrally with, and/or otherwiseassociated with any of the devices 12 described herein. Such devices maybe handheld and/or otherwise portable, and such exemplary systems 10 mayfurther include, for example, a receiver 28 and/or the remote source 92.

As shown in FIGS. 3-5, the signal emitter 14 can be coupled to, formedintegrally with, and/or otherwise associated with an unmanned aerialvehicle 18, an unmanned ground vehicle 22, and/or any of the otherunmanned devices 12 known in the art. One or more such unmanned devices12 may be remotely controlled. For example, these unmanned devices 12may be controlled to fly, traverse ground terrain, maneuver underwater,and/or otherwise move in response to a remote control signal.Alternatively, devices 12 such as the unmanned aerial vehicle 18 and theunmanned ground vehicle 18 may be preprogrammed to fly or traverseground terrain without dependence upon receipt of a remote controlsignal.

Further, as discussed above, the signal emitter 14 may be used inconjunction with, coupled to, formed integrally with, and/or otherwiseassociated with any known handheld devices, unattended devices, and/orunmanned marking devices. As shown in FIGS. 6 and 7, such devices 12 mayinclude any known self-righting device, such as a self-righting cameraball 24, an unattended ground device 26, and/or any other like device12. Such devices 12 may be useful in identifying a location and/orobject, and may be portable in order to be desirably positioned at theobject or location. For example, a self-righting device may be carriedto a desired location and thrown or jettisoned to a particular spot atthe desired location. The self-righting device may be weighted orotherwise constructed to right itself in a desired standing or otherwiseupright position upon landing or coming to rest. The unattended grounddevice 26, on the other hand, may be configured to be, for example,carried by hand to the object or location and desirably positioned insuch an upright position on stable ground.

In exemplary embodiments, one or more of the signal emitters 14described herein may be coupled to, formed integrally with, and/orotherwise associated with such devices 12, and may emit a beam or signalinforming a recipient of the beam or signal of information relevant tothe marked location/object. Such information may include the location ofa target, the location of friendly forces, the location of stored food,gear, or other resources, a perimeter or territory, the location of aninjured or distressed soldier, and/or other useful information. It isalso understood that in additional exemplary embodiments the signalemitter 14 may be used in connection with, coupled to, formed integrallywith, and/or otherwise associated with one or more known unmannedaqueous vehicles. Such vehicles may include, for example, underwatervehicles or robots as well as amphibious vehicles or robots. Using asignal emitter 14 in an underwater environment may require adjustment ofthe spectral band in which the signal emitter 14 operates.

Use of the exemplary signal emitters 14 described herein in conjunctionwith the handheld marking devices, unmanned aerial vehicles 18, unmannedground vehicles 22, unattended ground devices 26, self-righting devicessuch as self-righting camera balls 24, and/or the other devices 12described above has not been previously accomplished successfully due tothe complications and complexities associated with using such signalemitters 14 in association with such devices. For example, signalemitters 14 including one or more QCLs 30 are generally not capable ofhandheld use due to, for example, the heat generated by the QCL 30 (andcorresponding cooling requirements for efficient functionality), thepower requirements of known QCLs 30, and relative ease with which suchan expensive and delicate component may be damaged by sudden jarring,mishandling, being dropped accidentally, or other like movement. Untilnow, these and other operating requirements specific to the QCL 30 havemade it difficult, if not impossible, to utilize light, signal, beam,and/or radiation sources such as QCLs 30 for the marking,identification, signaling, and/or other operations described herein. Theexemplary embodiments of the present disclosure overcome these knownobstacles.

The receiver 28 may be any type of signal or beam detector known in theart. The receiver 28 may be configured to receive and interpret thebeam, signal, and/or other emissions of the signal emitter 14. Inaddition, the receiver 28 may be configured to locate, identify, anddistinguish such emissions from other similar emissions. As a result,the receiver 28 may be used to locate, identify, and distinguish one ormore friendly emissions/signal emitters 14 from similar foeemissions/signal emitters 14. Thus, the particular receivers 28described herein may be compatible with the signal emitters 14 of thepresent disclosure. The receiver 28 may be handheld and/or portable, andmay be conveniently used in any of the combat or other applicationsdiscussed herein. In additional exemplary embodiments, the receiver 28may be mounted in or on a ground vehicle, a rotary wing aircraft, afixed wing aircraft, or any of the firearms discussed above.

As shown in FIGS. 3 and 4, in an exemplary embodiment, the signalemitter 14 may be disposed on and/or otherwise connected to theunderside 16 of the unmanned aerial vehicle 18. Positioning the signalemitter 14 in this way may assist in cooling, for example, the QCL 30 ofthe signal emitter 14. In particular, positioning the signal emitter 14on the underside 16 of such a device 12 may keep the signal emitter 14substantially shielded from, for example, the sun. Such positioning mayprovide substantial cooling in, for example, the desert or othertemperate environments. In additional exemplary embodiments, the signalemitter 14 may be disposed elsewhere on the unmanned aerial vehicle 18,such as at the top of the fuselage or at one of the wings. Suchpositioning may assist with and/or otherwise facilitate communicationbetween, for example, two or more friendly unmanned aerial vehicles 18.

In addition, disposing the signal emitter 14 on an outer surface of suchmoving devices 12 may enable, for example, wind and/or ambient air tocool the QCL 30 as the device 12 moves. Such cooling may be particularlyeffective in relatively fast-moving devices 12 such as, for example, theunmanned aerial vehicle 18. In such exemplary embodiments, the housingconfiguration described with respect to FIG. 2 may be employed or,alternatively, the housing 20 may be omitted and the signal emitter 14may be formed integrally with the device 12.

In an exemplary method of the present disclosure, the signal emitter 14may be disposed on, coupled to, formed integrally with, and/or otherwiseassociated with the unmanned device 12 prior to its departure. When inthe proximity of friendly forces, such forces may be equipped with areceiver 28 configured to detect the signals or beams emitted by thesignal emitter 14, and thereby distinguish the friendly unmanned device12 from other devices. Such a determination may be made based on thebeam or signal emitted by the signal emitter 14. In addition, the signalor beam may be detected and distinguished, while the signal emitter 14and the device 12 to which it is connected are approximately 4 km ormore away. In additional exemplary embodiments, the signal or beam maybe detected and distinguished while the signal emitter 14 and the device12 are approximately 1 meter or more away. It is understood that thesignal, beam, and/or other emissions of the signal emitter 14 may bedistinguished from other like signals, beams, or emissions having, forexample, like frequencies, pulse signatures, information, and/or anyother identifiable or distinguishable characteristics or properties. Asdescribed above, in any of the embodiments described herein, the signalemitter 14 may be remotely activated and/or deactivated.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims

What is claimed is:
 1. A system, comprising: a hermetically sealedhousing configured for handheld use, the housing including a firstportion and an extension extending from the first portion, the extensionincluding an aperture; a quantum cascade laser (QCL) thermally connectedto the extension and at least partly disposed within the extension, theQCL being configured to emit a signal from the housing via the aperture,the signal having a wavelength between approximately 2 μm andapproximately 30 μm, and having a detectable signature identifying thesystem as friendly at a distance from the QCL greater than approximately1 m; a driver operably connected to the QCL, the driver being configuredto automatically increase or decrease at least one of a current or avoltage directed to the QCL based on a condition of an ambientenvironment external to the housing; and a passive cooling deviceconnected to the extension and thermally connected to the QCL, thepassive cooling device being configured to dissipate thermal energy fromthe QCL to the ambient environment.
 2. The system of claim 1, whereinthe first portion of the housing further includes a sealable compartmentsized to retain a removable power supply.
 3. The system of claim 1,wherein the detectable signature of the signal comprises at least one ofa wavelength, a frequency, or a pulse pattern.
 4. The system of claim 3,further including a grating disposed optically downstream of the QCL,the grating being adjustable during use of the system, and whereinadjusting the grating causes a first change in the detectable signatureof the signal.
 5. The system of claim 4, wherein the driver is disposedwithin the first portion of the housing, and is configured to cause asecond change in the detectable signature of the signal.
 6. The systemof claim 1, wherein the passive cooling device comprises at least onefin disposed on an exterior surface of the extension.
 7. The system ofclaim 5, further comprising a power supply operably connected to thedriver.
 8. The system of claim 7, wherein the first portion of thehousing further includes a port configured to operably connect the powersupply to the driver.
 9. The system of claim 1, wherein the housingincludes an isolation compartment disposed therein and isolating the QCLfrom moisture.
 10. The system of claim 1, wherein the passive coolingdevice further comprises a phase change element configured to absorbheat energy from the QCL and to utilize the heat energy from the QCL tochange phase.
 11. A method, comprising: generating a signal using aquantum cascade laser (QCL), wherein the QCL is disposed within ahermetically sealed housing configured for handheld use, the housingincluding a first portion, and an extension extending from the firstportion, the extension including an aperture, the QCL being thermallyconnected to the extension and at least partly disposed within theextension, the QCL emitting the signal from the housing via theaperture, and the signal having a wavelength between approximately 2 μmand approximately 30 μm, and having a detectable signature identifiableas friendly at a distance from the QCL greater than approximately 1 m;controlling a driver operably connected to the QCL to automaticallyincrease or decrease at least one of a current or a voltage directed tothe QCL based on a condition of an ambient environment external to thehousing; and dissipating thermal energy, from the QCL to the ambientenvironment, using a passive cooling device connected to the extensionand thermally connected to the QCL.
 12. The method of claim 11, furthercomprising changing the detectable signature of the signal by adjustinga position of a grating disposed optically downstream of the QCL. 13.The method of claim 11, further comprising changing the detectablesignature of the signal using the driver, the driver being disposedwithin the first portion of the housing and operably connected to apower supply.
 14. The method of claim 11, wherein the passive coolingdevice comprises at least one fin disposed on an exterior surface of theextension.
 15. The method of claim 11, wherein the housing includes anisolation compartment disposed therein, the isolation compartmentincluding at least one of a seal and an absorbent material isolating theQCL from moisture, and wherein the QCL is disposed within the isolationcompartment.
 16. A method, comprising: providing a hermetically sealedhousing configured for handheld use, the housing including a firstportion, and an extension disposed on and extending away from the firstportion, the extension including an aperture; thermally connecting aquantum cascade laser (QCL) to the extension, the QCL being at leastpartly disposed within the extension and configured to emit a signalfrom the housing via the aperture, the signal having a wavelengthbetween approximately 2 μm and approximately 30 μm, and having adetectable signature identifying the system as friendly at a distancefrom the QCL greater than approximately 1 m; operably connecting adriver to the QCL, the driver being configured to automatically increaseor decrease at least one of a current or a voltage directed to the QCLbased on a condition of an ambient environment external to the housing;and thermally connecting a passive cooling device to the QCL, thepassive cooling device: being connected to the extension, and configuredto dissipate thermal energy from the QCL to the ambient environment. 17.The method of claim 16, further comprising connecting a divergent lensto the housing, the divergent lens being disposed optically downstreamof the QCL and at least partly within the extension.
 18. The method ofclaim 16, the driver being disposed within the first portion of thehousing.
 19. The method of claim 18, further comprising operablyconnecting a power supply to the driver.
 20. The method of claim 16, thedriver being configured to: direct a first current to the QCL untilreceiving an activation signal, and direct a second current to the QCL,greater than the first current, in response to receiving the activationsignal, wherein directing the second current to the QCL causes the QCLto begin emitting the signal.
 21. A system, comprising: a hermeticallysealed housing configured for handheld use, the housing including: 1) afirst portion, the first portion defining a first internal space of thehousing having a first configuration, 2) an extension disposed on andextending away from the first portion, the extension defining a secondinternal space of the housing having a second configuration differentfrom the first configuration, the extension including: an aperture, andat least one of a lens and a window disposed at the aperture, and 3) anisolation compartment disposed within at least one of the first portionor the extension, the isolation compartment having a seal configured toblock passage of moisture from the at least one of the first portion orthe extension to the isolation compartment; a quantum cascade laser(QCL) disposed within the isolation compartment, the QCL being thermallyconnected to a wall of the extension and configured to emit a signalfrom the housing via the aperture, the signal having: 1) a wavelengthbetween approximately 2 μm and approximately 30 μm, and 2) a detectablesignature identifying the system as friendly at a distance from the QCLgreater than approximately 1 m; at least one fin disposed on an exteriorsurface of the wall, the at least one fin being configured to dissipatethermal energy from the QCL to an ambient environment external to thehousing; a driver disposed within the first internal space of the firstportion and operably connected to the QCL, wherein operation of thedriver causes the QCL to emit the signal having the detectablesignature, the driver being configured to automatically increase atleast one of a current or a voltage directed to the QCL based on acondition of the ambient environment; and at least one port coupled tothe first portion of the housing and operably connected to the driver,the at least one port being configured to receive a control command andto direct the control command to the driver.